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Visual Only: 150mm Triplet APO vs 14" Dobsonian

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#1 jag32

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Posted 24 July 2018 - 03:52 PM

Just as the subject says, for visual only, what will give more impressive views, a TOA150 or a 14" Obsession Dobsonian?

#2 bobhen

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Posted 24 July 2018 - 04:05 PM

You asked the same question in the reflector forum so I'll give the same answer here...

 

Depends: what do you want to observer?

Very larger deep sky objects
Small deep sky objects
Sun
Moon
Planets
Double stars

It also depends on your location and seeing? Where do you live? Can your location’s seeing support even a 10-inch aperture on the vast majority of nights or only maybe 2 nights or less per year?

How dark is your observing location? Will you need to travel to a dark sky location?

Answer the above and we can make a more useful recommendation.

Bob


Edited by bobhen, 24 July 2018 - 05:42 PM.

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#3 PETER DREW

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Posted 24 July 2018 - 04:06 PM

Depends a great deal as to what you're looking at. The Tak will provide better looking star images, useful for doubles but stars in a globular cluster will look much more impressive in the 14". For all round performance visually I would prefer the 14". It would be ideal to have both!


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#4 kfiscus

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Posted 24 July 2018 - 04:22 PM

14".


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#5 overnight

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Posted 24 July 2018 - 04:23 PM

+1 to 14".

 

Tak will have neat and great images, but can't beat 14" of aperture.



#6 Sam M

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Posted 24 July 2018 - 04:25 PM

I recently had occasion to compare my 12" dob with a TOA 130 on Saturn.  The seeing wasn't great, and I didn't spend time going back and forth, but to my eye the sharpness was the same, and the dob was brighter.  At the risk of stating the obvious, the quality and thermal equilibrium of the mirrors in the Dob would make all the difference.


Edited by Sam M, 24 July 2018 - 04:27 PM.

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#7 Astro-Master

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Posted 24 July 2018 - 04:39 PM

Webster telescopes has a 14.5" f4.5 with a Zambuto mirror, you can upgrade to a quartz mirror for even better planetary views.  I'll bet with the Zambuto quartz mirror it would give better planetary views in good seeing than the TOA 150.  Deep sky objects would be no contest.  


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#8 jakecru

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Posted 24 July 2018 - 05:46 PM

I would vote the 14 as well (if it is a good mirror), but the Tak may be the nicer built scope (definitely more pricey). With the budget of the 150, you could easily get a top quality premium primary and secondary mirror set and dominate the optical performance of the 150 (16" or 14.5" Zambuto/Lockwood/Lightholder/etc(other good makers). with 1/30 wave antares secondary, feathertouch focuser, cooling fans, etc. etc.). With the budget of a TOA 150, you could get a TSA 120, TOA 130, or TEC 140 and a nice quality dob. 

 

To strictly answer your question and assuming the mirrors in the obsession are good, 

 

On a good night with good seeing, both scopes will perform well. Coma will dominate the edge of the field in the dob unless it is corrected with a coma corrector.The Tak will be a easier to set up. The obession will take longer to cool down (especially true if it is a 2" thick mirror). The 14" will need to be collimated accurately before every use (recommend a good collimator like Glatter laser and Tublug barlow attachment). Stars may appear sharper in the TOA 150 (I have never used one, but I would expect this result), but you will see a ton more stars and even fainter stuff in the 14. The 14 will also have more resolving power to split tight doubles, and the 14 will be able to handle more magnification on planets. If the seeing is not as good, the TOA may perform better on planets with a sharper image. Also the TOA should cool much faster. I would expect the image to break down faster at high magnifications with the TOA than with a well collimated and cooled 14" dob.

 

If you want to do any photography, TOA no question. For visual only, it depends on the circumstances, but I would take the 14. 



#9 CHASLX200

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Posted 24 July 2018 - 05:46 PM

Just as the subject says, for visual only, what will give more impressive views, a TOA150 or a 14" Obsession Dobsonian?

I think you mean a 15" Obsession.  I had one years ago with a super good OMI mirror. A 15" top notch Newt will kill the TOA150 for high power planet work in my seeing.

 

Both scopes are killers.  The TOA will win with lower power wider FOV's and also show razor sharp views of the planets and moon up to around 450x.   I have used powers over 1000x on my best nites with the 15" Obsession i owned.  The much bigger scope can take higher powers with a brighter image vs the 6" APO.

 

But i also have some of the best seeing you can wish for.  If you live in a area of so so seeing then the 6" could be a better choice.  For deep sky the bigger Dob will see much more and much more brighter views of globs and galaxies.  If i had to pick again, the 15" Obsession would be my choice.



#10 TheFacelessMen

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Posted 24 July 2018 - 06:21 PM

The TOA150 might show nice tighter stars, sharper views, no spikes a nice field of view but remember they are still only a F7.5 and 6 inch scope.

 

The 15 inch Obsession with a good mirror should outdo the TOA150 especially on dimmer deep space targets showing much more detail on galaxies and nebulae and resolve deeper into clusters.

 

Really they are complementary not competitive options so a TOA150 combined with the Obsession would be a great pairing.


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#11 turtle86

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Posted 24 July 2018 - 06:26 PM

Just as the subject says, for visual only, what will give more impressive views, the flagship Takahashi TOA150 or a 14" Obsession Dobsonian?

 

 

To me a Dob and apo are complementary scopes, as each is better at different things.  The Dob will go a lot deeper, and will be much better for most deep sky objects IMO.  Definitely the scope of choice for globular clusters, planetary nebulae and galaxies (except perhaps Andromeda).  The apo will have a wider field of view, and will be generally better for larger extended objects, and rich field observing.  The apo will generally yield more aesthetically pleasing views of stars. On planets the apo will give a pleasing view unless the seeing is bad. The Dob potentially has more of an upside on planets but a lot of things have to go right for it to give nice planetary views, including good thermal control and good collimation.


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#12 AxelB

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Posted 24 July 2018 - 10:43 PM

Get the large dob + a 4 or 5" refractor for wide field.

#13 gnowellsct

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Posted 24 July 2018 - 11:18 PM

An ill informed question.  Why choose?

 

c14 and ap900 cloudynights size.JPG

 

 


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#14 Astrojedi

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Posted 25 July 2018 - 12:26 AM

Your question is somewhat subjective but let me try...

 

In absolute & objective terms there is no debate. Even a 14” with average optics will significantly outperform a 6” of any design and highest quality optics on any target.

 

But...

 

There are many many other considerations in choosing a scope and some of them may be even more important than your question depending on personal preferences. 



#15 janapier

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Posted 25 July 2018 - 05:57 AM

My most recent scope acquisition is a SW Esprit 150ED. It is a really fine scope. Some 25 years ago, I had a Meade 10" SCT bought from Sedona Vacuum and Telescopes (!) and self-imported into Germany. This scope was out of collimation, badly baffled and had rough optics. Still, it gave better views of M13 then than the Esprit does now (I collimated and flocked it subsequently, of course). The moon and planets are a different story. Rough optics ("nice" halo around Jupiter even in completely dry and transparent air) really affect contrast. Add cool-down time and seeing susceptibility, and the Esprit is the better planetary scope, but at substantially higher cost. 

 

The (apparent) sharpness of a good frac on solar system objects sometimes has an unreal quality to it. The day before yesterday I observed Copernicus with the Esprit, and the image gave me goosebumps. You know all the metaphors: "like etched in stainless steel", bla bla. You'll actually see at least as much, likely more in the 14", but you won't have this impression of "no instrument could render a sharper image". 


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#16 terraclarke

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Posted 25 July 2018 - 06:50 AM

TOA150 without a doubt!


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#17 Alan French

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Posted 25 July 2018 - 07:22 AM

On the big planets..... TOA

Everything else 14"

Anyone living where the seeing can be excellent would see more with the 14-inch. No contest.

 

But, if so, tracking would be helpful. 

 

Clear skies, Alan


Edited by Alan French, 25 July 2018 - 07:24 AM.

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#18 doctordub

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Posted 25 July 2018 - 07:36 AM

TOA 150.

 

CS

Jonathan


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#19 RAKing

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Posted 25 July 2018 - 07:56 AM

Anyone living where the seeing can be excellent would see more with the 14-inch. No contest.

 

But, if so, tracking would be helpful. 

I agree with this -- But I don't like diffraction spikes and star "blobs" caused by the CO and its vanes.

 

I want tracking and pin point stars, so please send that TOA 150 to me and we can both be happy!  cool.gif 

 

Ron


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#20 Tamiji Homma

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Posted 25 July 2018 - 09:21 AM

Just as the subject says, for visual only, what will give more impressive views, a TOA150 or a 14" Obsession Dobsonian?

 

When you have a doubt between two, you are not ready for one.

 

TOA150 without a doubt!

 

Hi Terra,

 

You are ready :)

 

Tammy


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#21 Jeff B

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Posted 25 July 2018 - 10:04 AM

My most recent scope acquisition is a SW Esprit 150ED. It is a really fine scope. Some 25 years ago, I had a Meade 10" SCT bought from Sedona Vacuum and Telescopes (!) and self-imported into Germany. This scope was out of collimation, badly baffled and had rough optics. Still, it gave better views of M13 then than the Esprit does now (I collimated and flocked it subsequently, of course). The moon and planets are a different story. Rough optics ("nice" halo around Jupiter even in completely dry and transparent air) really affect contrast. Add cool-down time and seeing susceptibility, and the Esprit is the better planetary scope, but at substantially higher cost. 

 

The (apparent) sharpness of a good frac on solar system objects sometimes has an unreal quality to it. The day before yesterday I observed Copernicus with the Esprit, and the image gave me goosebumps. You know all the metaphors: "like etched in stainless steel", bla bla. You'll actually see at least as much, likely more in the 14", but you won't have this impression of "no instrument could render a sharper image". 

Boy, I can relate to that.  I can't tell you how many times I've seen that super HD, 4K view myself but also there are the comments made during out reach, especially viewing the Moon and Saturn.  There are, of course,  the "WOWs",  "OMGs" and "It's soooo beautifuls" but many people say essentially "It's fake, your hanging a picture in front of the scope!".  There is just something about a live feed to the brain (especially with bino-viewrs) from a quality refractor that rings that bell.

 

That being said, I'm having those moments too with a truly excellent 11" F7 newtonian with a CZ mirror that I've carefully set up, cooled and collimated.  When the seeing allows, WOW, OMG....smile.gif

 

So, for me the short answer is with equal quality optics and when things literally line up, the 14" will be the superior instrument, seeing and cooling permitting (!).

 

Jeff


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#22 Jon_Doh

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Posted 25 July 2018 - 10:29 AM

I agree with this -- But I don't like diffraction spikes and star "blobs" caused by the CO and its vanes.

 

I want tracking and pin point stars, so please send that TOA 150 to me and we can both be happy!  cool.gif

 

Ron

Don't forget coma.


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#23 RAKing

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Posted 25 July 2018 - 10:58 AM

Don't forget coma.

chair.gif   OMG! How could I forget all those wonderful seagulls flying around in space?  I must have repressed those memories.

 

Should I thank you for reminding me, or be mad at you for dredging up a painful reminder?  lol.gif

 

I will still take that 3D look at planets through my refractors anytime.  I don't care how much brighter the view is through a Newt.

 

Cheers,

 

Ron


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#24 Alan French

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Posted 25 July 2018 - 11:51 AM

chair.gif   OMG! How could I forget all those wonderful seagulls flying around in space?  I must have repressed those memories.

 

Should I thank you for reminding me, or be mad at you for dredging up a painful reminder?  lol.gif

 

I will still take that 3D look at planets through my refractors anytime.  I don't care how much brighter the view is through a Newt.

 

Cheers,

 

Ron

Not just brighter, but far more detailed. I've had views of planets through large Newtonians, notably Mars and Jupiter, under exceptional seeing that can simply not be duplicated through any 150mm apochromat. 

 

Clear skies, Alan


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#25 Astrojedi

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Posted 25 July 2018 - 12:00 PM

I think we have to be careful with generalizations when commenting on APOs vs. Reflectors.

 

While I generally agree with what is being said we need to be careful to separate the subjective from the objective and also ensure we are comparing instruments of comparable quality / cost irrespective of design.

 

Subjectively, yes you could say the view in an ED apo is better but objectively a 14" will have significantly higher light grasp, resolution and contrast vs. a 6". There is just no competition.

 

One my second point....

 

My 14" has a high strehl mirror and a 19% obstruction secondary. It costed me the same as a premium 6" APO (but still much cheaper on a $ / aperture basis). With the coma corrector the views it produces are just sublime - pinpoint stars and no coma anywhere in the fov even with my 82deg 30mm. The airy disk is so tight it is almost indistinguishable from an apo.

 

In excellent seeing I can see festoons within festoons on Jupiter and swirling clouds within the GRS - views that are unmatched by any 6" apo. I doubt even a 8-10" apo will come close.

 

But I still use my 4" and 5" refactors and my C9.25 more simply because they are "easier" given my limited time. The 14" comes out on the weekends or on dark site trips. To me the refactors have a completely different value proposition.


Edited by Astrojedi, 25 July 2018 - 12:06 PM.

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